1 ) An astronaut in space comes to know of an explosion on a near planet . So the astronaut came to know about this explosion because of . . . . . . . . . . , A ) light , B ) sound , C ) both of these , D ) None of these ,

1 ) An astronaut in space comes to know of an explosion on a near  planet . So the astronaut came to know about this explosion because of . . . . . . . . . . ,

A ) light ,                                                       B ) sound ,

C ) both of these ,                                        D ) None of these ,

Correct Answer : -  A ) light ,

Because in space light travels but sound does not travels , so he saw the explosion as a light .

 

2 ) The unit of focal length of Lens is . . . . . . . . . . ,

A ) diopter ,                                                                B ) seimen ,

C ) hertz ,                                                                   D ) None of these ,

Correct Answer : -   A ) diopter ,

 

3 ) Temperature coefficient of resistance : -

4 ) A ( 100 W , 200 V ) bulb is connected to a 160 V power supply . The power consumption would be : -

A ) 42 W ,                                                                  B ) 64 W ,

C ) 92 W ,                                                                  D ) None of these ,

Correct Answer : -   B ) 64 W ,

Solution : -

5 ) A 50 volt battery is connected across 10 ohm resistor . The current is 4.5 A . The internal resistance of battery is : -

A ) 1.1  ohm   ,                                                          B ) 3.8  ohm   ,

C ) 4.1  ohm   ,                                                          D ) None of these ,

Correct Answer : -   A ) 1.1  ohm   ,

Solution : -

We have a formula : -

I   =   V  /  ( R + r )  ,

So ,  ( R + r )  =  V / I  ,

So ,  r = ( V / I ) – R  ,

r  =  ( 50 / 4.5 ) – 10  ,

r  =  1.1  ohm   ,  Answer .

OR

6 )  

Five resistances have been connected as shown in figure . The effective resistance between  A and B  is : -

A ) 14 / 3 ,                                                                  B ) 19 / 2 ,

C ) 23 ,                                                                       D ) None of these ,

Correct Answer : -   A ) 14 / 3 ,

Solution : -

7 )

Seven resistances are connected as shown in figure . The equivalent resistance between  A and B is : -

A ) 1 Ω ,                                                                     B ) 4 Ω ,

C ) 11 Ω ,                                                                   D ) None of these ,

Correct Answer : -   B ) 4 Ω ,

Solution : -

8 ) The number of neutrons in parent nucleus which gives N¹⁴  on beta emission is : -

A ) 7 ,                                                              B ) 8 ,

C ) 9 ,                                                             D ) None of these ,

Correct Answer : -   B ) 8 ,

Solution : -

6C¹⁴ -----------> 7N¹⁴ + -1e.

So no. of neutrons in parent nucleus is : -       14 - 6 = 8 .